---

s1 = input()
s2 = input()
n = int(input())

if len(s1) > n and len(s2) > n:
    if len(s1) < len(s2):
        print(s1)
    else:
        print(s2)
elif len(s1) > n:
    print(s1)
elif len(s2) > n:
    print(s2)
else:
    print(n)